The present invention relates to an adaptive cruise control system which executes a following control of a host vehicle relative to a preceding vehicle.
Japanese Patent Provisional Publication No. Heisei 7-76237 discloses a vehicle drive control system which estimates a vehicle speed of a preceding vehicle when an inter-vehicle distance detector loses sight of the preceding vehicle, in order to prevent a host vehicle from excessively approaching the preceding vehicle.
However, such a vehicle drive control system estimates the vehicle speed of the preceding :vehicle on the basis of the preceding vehicle speed at a moment before the inter-vehicle distance detector loses the sight of the preceding vehicle. Therefore, in some cases such that the preceding vehicle is decelerated just after the inter-vehicle distance detector loses the sight of the preceding vehicle, such an approach of the host vehicle to the preceding vehicle impresses the driver as strange feeling.
It is therefore an object of the present invention to provide an adaptive cruise control system which control a vehicle speed of a host vehicle so as to prevent a driver from having strange feeling.
An aspect of the present invention resides in an adaptive cruise control system which is for a host vehicle and which comprises a preceding vehicle detecting device, a vehicle speed detecting device and a controller. The preceding vehicle detecting device detects a preceding vehicle ahead of the host vehicle. The vehicle speed detecting device detects a host vehicle speed of the host vehicle. The controller is coupled to the preceding vehicle detecting device and the vehicle speed detecting device. The controller is arranged to execute a vehicle speed control of the host vehicle on the basis of detection results of the preceding vehicle detecting device and the vehicle speed detecting device, and to cancel the vehicle speed control when the preceding vehicle detecting device is incapable of detecting the preceding vehicle.
Another aspect of the present invention resides in a method of controlling an adaptive cruise of a host vehicle. The method comprises a step for detecting a preceding vehicle ahead of the host vehicle, a step for detecting a host vehicle speed of the host vehicle, a step for executing a vehicle speed control for controlling the host vehicle speed on the basis of a detected state of the preceding vehicle and the detected host vehicle speed, and a step for canceling the vehicle speed control when the preceding vehicle detecting means is incapable of detecting the preceding vehicle.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.